So out of curiosity I stumbled across this site http://ie.microsoft.com/testdrive/performance/fishbowl/ and with my old system and firefox 36.0.1 on auto it ended up around 2250 fish, 25 cpu usage and about 360 MB of ram.
And 449 points on this site
https://html5test.com/
Any other tests/benchmarks? What you guys get?